To enhance the integration density of a semiconductor integrated circuit, it may be necessary to inspect fine and complicated pattern shapes formed therein.
However, the acquisition of a three-dimensional shape by cross-sectional observation using a transparent electron microscope (TEM) or the like is very expensive during working of a sample and observation of the sample.
Further, in the three-dimensional measurement using light, a size of an object to be observed is limited due to wavelength limitations of light. For example, it is difficult to observe a shape on a nanometer scale using light.
On the other hand, an image acquired by a scanning electron microscope (SEM), referred to as a shape contrast, contains information relating to a three-dimensional shape and hence, a method where a three-dimensional shape is reconstructed by making use of the shape contrast has been proposed.
However, a density distribution, which is two-dimensional information, contains a factor which affects density but not the shape contrast, thus giving rise to a drawback that results of inspection contain uncertainty.